1. Field of the Invention
The present invention relates generally to a radio VOD (Video-On-Demand) system. More particularly, the present invention relates to a radio VOD system that can provide various multimedia files through radio communication at the time desired by the user.
2. Description of the Related Art
A prior art radio VOD system comprises of a server, which is an information provider, a network, and an indoor receiver such as a set-top box. The server stores video information and its associated application software for controlling the video information in a bundle, and selectively transmits the video information to an end user device (i.e., set-top box) at the request of the end user.
In regard to the network of the VOD system, a wideband network is used which is capable of transmitting the video information at a rate of several Mbps. The set-top box, which is an indoor receiver installed in a home of the end user, serves as a terminal station of a wideband transmission line. The wideband transmission line is a physical transmission medium, and decodes digital information transmitted from the server. The decoded digital information is displayed on a TV monitor. Furthermore, the set-top box transmits a user's request to the server.
At the present time, active research is being carried out on a method for building a radio VOD system between a base station and a mobile terminal using radio communication. Unlike the current prior art radio VOD system, a VOD system does not depend on a physical transmission line.
For example, a radio VOD system introduced by NTT company, Japan, is designed such that the base station and the mobile terminal can wirelessly exchange data using a frequency of 25 GHz at a rate of 10 Mbps for short distances of 50 to 100 m. The radio VOD system introduced by NTT company can be simultaneously accessed by a maximum of 16 users and can transmit information at a rate of up to 50 Mbps via the base station. However, such short distance of 50 to 100 m limits the practical use for such systems.
That is, such wireless VOD systems using the high frequency band is extremely limited by the permissible distance between the base station and the mobile terminal. To increase the permissible distance, it is necessary to increase significantly the costs of building the system. Further, since the number of users who can simultaneously access the system is limited to 16, it is not possible to meet the needs of many users exceeding such a limited number. In addition, since the high frequency band is used, the operating costs of the mobile terminal and the exchange increase as well.